Car battery negative earth

My MGB died on me today with a dead battery, I fitted a single Bosch S4100 from the two single 6 volt batteries on it about six years ago, and its been trickle charged when not in use.

I had the battery checked and its finished so a new one is needed.

I used the car the other day and it started ok but rather sluggish so I can tell if a battery is on the way out. My question is, if this happens again away from home can a jump start be done from a positive earth car to a negative earth.

Bob.

No reason why not - as long as the leads are connected correctly. No real difference than a battery standing on the floor next to the car?

Just don’thave the two vehicles touching while you do it.

Agreed, as long as the vehicles are not touching and you connect positive to positive and negative to negative I don't see why not.

I did try jump starting a two battery MGB once, but the linking cable wasn't on the terminals I expected them to be, so I had rather an exciting few seconds...

Yes, it can be a bit disconcerting to see thick copper jump leads sag...

What year is that? My MGBGT is standard negative earth. I put a single battery next to the spare wheel.

Disn't they have a battery under each seat?

Yes, there were two 6v batteries, one each side of the prop shaft under the rear seat. A rather pointless attempt at weight distribution. Higher capacity than a typical battery of the time but the extra cranking power was negated by the longer wire run. Later models had a more normal 12v in the engine bay I think. Because they were expensive I ran for a while with a spare battery in the passenger footwell and crock clips for cold starting. After a few minutes to recharge I would take off the negative clip.

u can see why the Mazda MX5 has taken over.....

when I lived in the States, had a bumper sticker that said.............

"the parts falling of this MG are quality, built in Britain".........

thankfully all(most) all that rubbish is long gone......

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Barrie is correct, I can keep up with traffic with my 1967 MGB today, but tend to keep to 60mph so really a slow old git with a cap on.

Bob.

Edited By BOB BLACKSHAW on 24/09/2018 08:59:10

Assuming you have two 6v batteries, shouldn't you replace both at the same time as they will have different charging requirements because with age, the batteries change due to sulphating.
Bob with a 6v Austin 7.

Hi Bob

Can’t see the s4100 battery you mention, is it a 12volt, if not why not change to a single 12v as most mgb owners do, fit plastic battery buckets in the wells and use the one on the left for tool storage.

I would never advise having a loose battery in the passenger we’ll or anywhere else for that matter whilst you are driving, a small bump or rapid stop could be catastrophic.

Regarding parts falling off mgb”s, I have just passed my 78 B to my nephew as we are getting a bit too stiff to use it as it should be. It is as sound as the day it was bought as it was zebarted and waxoyled from new.

Most cars will fall apart in time if they are not properly used and maintained.

Ian

I've fitted a Bosch S4 000 its a single 12 volt fitted rear of the drivers seat, early models have two battery compartments. I converted it from the two 6 volt batteries which were a problem getting at them as you had to keep topping up with distilled water regularly.

A single 12 volt are around £50 compared to the 6 volt at £70 each, I have a cut off switch near the battery, which should be fitted to older cars in case of electrical fires. Its fitted ok and passed the MOT.

MOT are not needed on cars 40 years old now but I have mine done anyway for safety reasons, also in case of accidents theirs no insurance get out.

Bob

Edited By BOB BLACKSHAW on 24/09/2018 10:46:43

Bob,

You might want to check your charging regulator especially if you still have the dynamo, constant top ups says you have overcharging.

My Myford lathe will go on for ever but I love to take the micky out of my mate's MGB.

Really?

Tim

The starter takes a LOT of Amps, (at least 200 if not more) so make sure that the terminals, (post and connectors) are clean . Any resistance there will a) cause a voltage drop on load, and b) do the same thing when charging, so the regulator sees a battery with higher voltage than it actually has, and reduces the supply, leading to a partially charged battery. Also make sure that the earth connections between battery and chassis, and the engine and chassis are clean and tight.

Once they are; seal them against moisture and corrosion ingress, by coating with grease, or Waxoyl.

(A Rover 200 used to fail it's rear hub bearings because of pitting. The engine/chassis earth lead had been omitted, so that the HT was earthing through the bearings! The earth lead cured the problem.

A VW Beetle cranked slowly. The earth lead was badly corroded. A new lead greatly increased the cranking speed.

Howard

I once tried to crank a just-installed engine, prior to trying to start it, to raise oil pressure (spark plugs not fitted). Wondered why it did not crank until I saw smoke coming off the fuel line! The fix was obvious enough!

Has the OP considered fitting a battery isolator rather than trickle charging? I fit maintenance free batteries to my classic cars and find that isolating the battery if the car is not going to be used for a week or two seems to suit the batteries, no trickle charge necessary. I've had poor results with trickle chargers in the past so don't bother with them now. I remove the batteries for the winter lay-up, bring them in to the house. I occasionally put them on the charger during the winter, usually to check the battery rather than charge it, seems to keep them in good order.

On a lighter note, if you want to tease an MGB owner, call it a Cambridge GT!

John

I've fitted a isolator and have the maintenance free battery, I will try not using the trickle charge on this one and see how it goes.

I noticed John used OP, does that mean OAP, if so I'm not there yet, 63 and 3 months old. The government has added another year on my sentence so 66 before the bus pass, if I'm lucky to get it. The wife has worked since 15 no time out and she will be sixty five and six months, so that's six and a half years total for the both of us, a bit of a sour subject that one.

And for the Cambridge GT, it does piss you off a bit, but the spare parts are cheap.

Bob.